Video report by ITV News correspondent Juliet Bremner
Black Lives Matter protesters who called for a "nationwide shutdown" brought traffic heading to Heathrow Airport to a standstill.
Protesters unveiled a giant banner saying "This is a Crisis" before lying in the middle of the road on Friday morning.
Holidaymakers making their way to the airport were disrupted.
Protests have also taken place in Nottingham and Birmingham.
The protest group called for a "nationwide shutdown" on Wednesday.
A Metropolitan Police spokesperson told ITV News that 10 people had been arrested over the incident.
Earlier tailbacks have now cleared and the motorway around the airport is open and "operating as normal", the spokesperson added.
No injuries have been reported.
Heathrow Airport said the protest did not appear to cause people to miss flights.
Demonstrations are also taking place in Nottingham and Birmingham.
ITV Central said people have been lying on the tracks of the Nottingham tram line.
Nottinghamshire Police have said that four people have been arrested on suspicion of causing the wilful obstruction of a highway.
Activists blocked a road near Birmingham Airport.
Footage showed police dragging protesters out of the road in a bid to ease congestion.
(Credit: Rachel Bulmer)
Black Lives Matter is an American social justice movement that started around three years ago in response to repeated police killings of black people.
In recent months, protests and activism around Black Lives Matter has been stepped up as several unarmed black men have been shot and killed by US police officers.
The movement in Britain is small but growing, with activists arguing for justice and equality from the police when it comes to the black community.
Wail Qasim, who was at the Heathrow protest, told ITV News: "Since 1990, at least, we've seen zero convictions for over 1,563 deaths in police custody."
The protests have been organised for the day after the anniversary of Mark Duggan's death, which sparked riots nationwide in the summer of 2011.
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